230 



ADVANCED ELECTRICITY AND MAGNETISM. 



and BB are suddenly connected the line oscillates electrically,* 

 and Figs. 164, 165, 166 and 167 show four successive stages of 

 one half of a complete oscillation. The electrical behavior of 



charge 



current 



current 



charge 



Fig. 164. 



Fig. 165. 



Fig. 166. 



- - 4- 



4- 4- 



Fig. 167. 



the line is completely represented in Fig. 168. When the two 

 halves of the line in Fig. 163 are suddenly connected, a ribbon 

 wave FF shoots to the right from the middle point, and a ribbon 

 wave DD shoots to the left from the middle point; and these 

 ribbon waves are repeatedly reflected or turned back at the open 

 ends of the line, as indicated in Fig. 168. To find voltage 

 distribution over the line at any instant the initial voltage dis- 



* This particular case is mathematically identical to the vibration of a guitar 

 string when it is plucked at its middle point. 



